June 19, 2026Journal of the American College of Cardiology205 citationsOpen Access
Capillary density of skeletal muscle
Key Result
Class II-III chronic heart failure was associated with a significant reduction in skeletal muscle capillary density compared to healthy controls (1.42 vs. 1.74 endothelial cells/fiber, p=0.02).
Key Points
- This study aims to evaluate how capillary density in skeletal muscle relates to exercise intolerance in chronic heart failure.
- Examined skeletal muscle biopsies from 22 male patients with CHF and 10 age-matched controls.
- Measured peak oxygen consumption, myosin heavy chain isoforms, and microvascular density using cell-specific antibodies.
- Analyzed the relationship between capillary density and maximal oxygen consumption.
- CHF patients had reduced peak oxygen consumption (15.0±2.5 vs. 19.8±5.0 ml x kg(-1) x min(-1), p <0.05).
- Capillary density in CHF was lower (1.42±0.28 vs. 1.74±0.35 cells/fiber, p = 0.02).
- In CHF, capillary density was inversely related to maximal oxygen consumption (r = 0.479, p = 0.02).
Study Design
Type
Cross-Sectional (n=32)
Multicenter
Yes
Structured PICO
Does capillary density of skeletal muscle differ between patients with class II-III CHF and normal controls, and does it correlate with exercise intolerance?
P
Population
32 sedentary men, comprising 22 with class II-III chronic heart failure and 10 age-matched healthy controls, evaluated for skeletal muscle capillary density and exercise capacity.
C
Comparator
Age-matched normal sedentary male controls
O
Outcome
Capillary density of skeletal muscle (measured as endothelial cells/fiber via immunohistochemical analysis)surrogate
A reduction in skeletal muscle microvascular density may precede other skeletal muscle alterations and play a critical role in the exercise intolerance characteristic of patients with chronic heart failure.
Main Result
Absolute Event Rate: 1.42% vs 1.74%
p-value: p=0.02
Limitations
- Cardiac output was not measured, limiting the ability to fully separate central hemodynamic from peripheral contributions to exercise intolerance.
Abstract
OBJECTIVES: The study was conducted to determine if the capillary density of skeletal muscle is a potential contributor to exercise intolerance in class II-III chronic heart failure (CHF). BACKGROUND: Previous studies suggest that abnormalities in skeletal muscle histology, contractile protein content and enzymology contribute to exercise intolerance in CHF. METHODS: The present study examined skeletal muscle biopsies from 22 male patients with CHF compared with 10 age-matched normal male control patients. Aerobic capacities, myosin heavy chain (MHC) isoforms, enzymes, and capillary density were measured. RESULTS: The patients with CHF demonstrated a reduced peak oxygen consumption when compared to controls (15.0+/-2.5 vs. 19.8+/-5.0 ml x kg(-1) x min(-1), p <0.05). Using cell-specific antibodies to directly assess vascular density, there was a reduction in capillary density in CHF measured as the number of endothelial cells/fiber (1.42+/-0.28 vs. 1.74+/-0.35, p = 0.02). In CHF, capillary density was inversely related to maximal oxygen consumption (r = 0.479, p = 0.02). The MHC IIx isoform was found to be higher in patients with CHF versus normal subjects (28.5+/-13.6 vs. 19.5+/-9.4, p <0.05). CONCLUSIONS: There was a significant reduction in microvascular density in patients with CHF compared with the control group, without major differences in other usual histologic and biochemical aerobic markers. The inverse relationship with peak oxygen consumption seen in the CHF group suggests that a reduction in microvascular density of skeletal muscle may precede other skeletal muscle alterations and play a critical role in the exercise intolerance characteristic of patients with CHF.